Oxalis Triangularis: False Shamrock, Truly Glorious
Oxalis triangularis, the false shamrock, is simply stunning. Learn how to grow it indoors and out with our complete grower's guide!
The purple leaves and small flowers of the Oxalis triangularis plant are distinctive. It’s often called the “false shamrock” because its leaves resemble those of shamrocks. This isn’t a shamrock, though — shamrocks are a form of clover, and this is anything but!
Nearly heart-shaped or triangular leaves move depending on the ambient light. At night, the love plant’s leaves will fold down like an umbrella, and the flowers close. But once morning comes, they reopen and stretch up to catch the sun.
A variety of purple wood sorrel, this foliage plant’s a great choice as an ornamental. It’s lovely both indoors and out and can be the perfect houseplant. It’s easy to care for as long as it’s got the right temperature, and it’ll come back year after year!
For those of us in warm climates, the Oxalis triangularis plant works well both in xeriscaping and in regular landscaping. You’ll find it to be surprisingly adaptable so long as you keep it mulched. It also can make for an unusual ground cover plant in warm climates!
So why look for a four-leaved clover when you can have a three-leaved lucky shamrock plant? Let’s go over everything your Oxalis triangularis could need to explode into growth!
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Quick Care Guide
|Common Name(s):||False shamrock, purple shamrock, love plant, purple wood sorrel|
|Scientific Name||Oxalis triangularis|
|Zone:||7-11, but performs best in zones 8-9|
|Height & Spread:||15″-18″ tall, will spread indefinitely by rhizomes|
|Light||Full sun to partial shade|
|Water:||Prefers damp soil, can tolerate periods of dry conditions|
|Pests & Diseases:||Sucking pests. Also susceptible to rust, mildew, botrytis, root rot.|
All About False Shamrock
Oxalis triangularis is native to several countries in South America. There’s a bit of confusion about the false shamrock – namely, what its botanical name is. Officially, it’s Oxalis triangularis. It’s sometimes listed as its synonym, Oxalis regellii subsp. triangularis.
But despite the name confusion, purple shamrocks are glorious plants. The leaves are formed of three separate leaflets, each one triangular in shape. As the sun rises, these leaves open up wide to capture the sun’s rays. In the evening, they fold down like an umbrella.
The leaves of Oxalis triangularis may be purple, nearly black, reddish, or green in color. These vary by subspecies or cultivar, but all show the same responsiveness to light. You can actually go out at sunrise or sunset and watch the leaves “wake up” or “fall asleep”!
The leaves will also move in response to being bumped or windblown. By folding itself up, Oxalis triangularis protects its foliage from damage.
Each leaf is attached to a petiole, a slender stem that rises up from a rhizome hidden beneath the soil. Flower stalks also rise directly from this tuberous rhizome to form buds. The resulting five-petaled flowers may be white, pale pink, pale lavender, or a mix of any of the above.
It’s a winner of the Royal Horticultural Society’s Award of Garden Merit, and this award’s well-deserved. This fascinating plant deserves a place in every home and garden!
Types of False Shamrock
As a general rule, all false shamrock falls into one of three subspecies. Those are subsp. papilionacea, subsp. lepida, and subsp. glabrifolia.
All three subspecies of Oxalis triangularis are very similar, but the coloration varies. More commonly, you’ll find these sold under specific cultivar names. There’s a wide range of names out there, and many are specific to the company where they originate.
We’ll loosely cover three of those cultivars now. Just be aware that this isn’t all that’s out there! Some species are reddish, others green, and still more purple to almost black. Their flower colors vary too. All are native to South America.
Oxalis triangularis ‘Francis’
This bright purple shamrock is an absolute delight. One of the most popular cultivated forms, Francis oxalis, are vividly purple heirloom plants. White to lavender-pink blooms rise up from amidst the leaves during its flowering season.
Oxalis triangularis ‘Charmed Jade’
Still a false shamrock, Charmed Jade is bright green. If you’re looking for a variety that isn’t in the purple or red range, you’re in luck! While not as popular as the darker varieties, it’s still an absolute delight. Medium-green color with white or ivory flowers.
Oxalis triangularis ‘Ebony Allure’
Ebony Allure is a lovely Oxalis triangularis plant cultivar! With this one, zones 7-9 are recommended. Direct hot sunlight can burn the leaves very fast, so it’s best in partial shade. Its leaves can be so dark they’re mistaken for black. The flowers begin as a pale pink and fade to white.
Your love plant is going to be fairly self-sustaining. However, a few tips can help your plant truly shine. Our recommendations for its care should help you keep your plant healthy and happy!
Light & Temperature
Your false shamrock can tolerate a wide variety of lighting conditions, but they need a somewhat bright location. Sun or partial shade are perfect for this lovely plant. In cooler climates, Oxalis triangularis grows best in full sun conditions. This promotes vibrant color. Hotter climates should provide afternoon shade. While it can grow in full shade, it requires bright, indirect lighting.
Oxalis triangularis can be grown in zones 7-11 but performs the best in zones 8-9. Zone 7 growers should definitely opt for full sun conditions.
Where it’s very tolerant of light variables, it’s not as tolerant of temperature shifts. Oxalis triangularis cannot tolerate frost conditions or extreme heat. Hot conditions can cause the plant to weaken or enter a dormancy period. Temps under 50 degrees cause it to fail as well.
For best growth, maintain a temperature range between 60-80 most of the time for your plant. Never let it dip down into the 40s or lower without some form of protection. A cold frame can help extend your outdoor growing season for this plant.
Water & Humidity
Though drought-resistant once it’s established, Oxalis triangularis needs water to get started. Ensure you’re maintaining evenly-moist soil when the plants are young, and avoiding soggy soil. Once they’ve put down deeper roots, they can tolerate reduced watering.
Make sure to mulch around the base of these plants to prevent soil moisture evaporation. A good wood chip mulch can reduce the need for watering significantly. Three inches of chip mulch can retain some water and will aid in keeping the soil damp.
Avoid muddy conditions or soggy soil for your Oxalis triangularis plants. Standing water can create the right environment for fungal diseases to develop in.
Well-draining, humus-rich soil is perfect for false shamrock. It should hold moisture well but allow excess to drain away freely. Container-grown plants do very well in potting soil.
While purple shamrock can grow in clay soil, it prefers loose material that allows the roots to grow deep. Working compost through your soil can help with this. Adding coconut coir can also help to lighten up the soil density. Perlite will provide drainage in conjunction with the compost and coir. Most potting soil mixes contain all these ingredients, and amending garden soil with them works too.
If you’ve worked some compost into your soil, you shouldn’t need to fertilize your purple shamrock much the first year. For subsequent years, pull back the mulch layer. Spread compost on the soil’s surface, then cover up with mulch again.
As a general rule, oxalis does well even in poorly-fertilized conditions. There’s little need to use commercial fertilizer. You can opt for a slow-release fertilizer, but quality compost provides all your plants need.
Propagation from division or seed is best for the love plant.
Division is the most reliable method of propagating purple shamrock. Carefully work a shovel into the soil to loosen it. Try to avoid cutting the rhizomes that extend out from the plant. Once it’s been loosened, lift the plant from the soil and examine the root mass. There should be some larger tubers or “corms” with rhizomes extending from them. Each of those with its rhizome mass can form a new plant.
Gently separate the plant into clumps, trying to ensure each clump has a corm as well as plenty of rhizomes. Replant at the same depth they were planted before. Be sure the soil has plenty of compost worked in to give your new plants a good start. Your separated plants may droop for a few days after division as the roots settle in.
Seeds should be sown in spring after the soil has reached 60 degrees. Space your seeds at least an inch apart, and cover them with about an eighth of an inch of soil. Keep the soil consistently moist for the first growing season. Your new plants need more moisture than established ones would. In a few weeks, you’ll have Oxalis sprouts.
Growing oxalis in containers? Have no fear; repotting into fresh soil is as simple as can be!
Gently remove the purple shamrock from the pot and brush away the soil to reveal the Oxalis bulbs. If you want, divide the plant. Examine the roots for any signs of rot and trim off damaged portions with sterile shears.
Prepare your new, fresh soil. Be sure it’s well-draining and that it has plenty of compost worked through it. Using the new soil, replant your plant in the same pot or a slightly larger one at the soil line it was previously planted at. Make sure to leave room at the top of the pot for mulch!
It’s generally easier to divide overcrowded plants than to go up in pot size. In a few weeks, they’ll be adequately established, and the foliage begins to put off new growth.
Pruning Oxalis triangularis is actually very easy, and it doesn’t take long to do maintenance.
Remove spent flower stalks from your purple shamrock once the blooms fade. With clean pruning shears, you can snip off the stalk down at the plant’s base.
In the summer, your plant may begin to enter a dormancy period. Its leaves may turn brown, and it may look like it’s dying back. This is a normal response to hot weather! Trim back the browning foliage to about an inch from the plant’s base. If possible, move your plant to a cool and dark location and stop watering for 2-3 months. If you can’t move the plant, trim back the foliage to ground level and leave the mulch to keep the plant’s base cool.
You’ll find that your purple shamrock plant’s resistant to a lot of pests, although a few still come to call. Its diseases are mostly treatable, too. Let’s go over the problems which you’ll experience while growing this purple sorrel!
Temperature is usually one of the trickiest aspects to maintain when it comes to caring for purple shamrock. Your love plant prefers it to be between 60-80 degrees at all times. Many opt to grow them as house plants indoors where the climate is more regulated.
Up to twice a year, your plant may go dormant. In its dormancy, its leaves will brown, and it will appear dead. This doesn’t mean the plant’s dead! It’s just conserving its energy for a later flush of growth. When dormant, stop watering until it begins to show signs of new growth.
Most pests only use the wood sorrel family of plants as a temporary food source. They contain small amounts of oxalic acid, which tends to be more of an irritant for pests than a benefit.
The few which still strike purple shamrock are extremely common. Often, they’ll appear due to other infested garden plants. If you can eliminate these on your other plants, they seldom attack oxalis!
Aphids are common garden irritants. While these are less prone to attacking oxalis plants than others, they can still feed on them. Unfortunately, they can also spread plant diseases. Use neem oil to keep these at bay. Insecticidal soap also works well.
Whiteflies are another annoying sucking pest. They’re easy to identify because of the clouds of tiny white adults that appear in the garden. Both neem oil and other horticultural oils can keep them away. Insecticidal soap or a pyrethrin-based pesticide wipe them out.
Finally, our old nemesis, the spider mite, is a possible pest of purple shamrock. This annoying little arachnid will lay its eggs on leaves. It also may suck sap from the leaves and stems. They’re eliminated by the same treatments as aphids or whiteflies.
On a more positive note, you’ll find your love plant isn’t a target for deer or other nibbling mammals! They’re perfect for deer-resistant gardening.
For three of the following diseases, there are easy treatment options. The fourth is a bit riskier, but thankfully also less common!
Root rot is possible among plants in overly moist and warm conditions. To prevent this disease, practice proper watering of your in-ground or container-grown false shamrock plant. Symptoms may include yellowing of the lovely deep purple foliage or wilting and rot present around the base of the plant.
Rust is a fungal infection that causes purple shamrock leaves to yellow. The leaves eventually develop reddish, rusty-looking patches of spores. While this is most common when your plant’s going into its dormancy period, it may still happen at other times of the year. Use a fungicidal spray to get rid of it.
Powdery mildew is a normal garden irritant. This white, dusty-looking disease is easy to treat with neem oil. A biofungicide can also clear it right up.
Botrytis creates greyish “mold” patches, which are actually spores. This can spread to other plants quickly, so treat it with a copper-based fungicide. Biological fungicides also work.
Finally, the fourth issue is chlorotic ringspot. If yellowish rings begin to form on the purple shamrock leaves, you may have a problem. These rings will fade into blotches or streaks of yellow. It’s a systematic issue and can’t be resolved through treatment. Keep aphids away, as they’re believed to spread chlorotic ringspot. Remove infected plants and destroy them to prevent further spread.
Frequently Asked Questions
Q: Is Oxalis triangularis poisonous to humans?
A: Oxalis triangularis contains very small amounts of oxalic acid. This can be an irritant to people in large doses. However, the doses found in your purple shamrock are so small that they’re harmless to most humans. In fact, some people eat false shamrock leaves, flowers, and roots! They have a slightly bitter but tasty flavor.
To avoid any dangers from oxalic acid, you may want to cook your leaves and roots, which reduces its risk. Use it in limited quantities. While you can eat it raw, a few leaves or flowers in a salad is plenty.
Q: Is false shamrock dangerous for my pets?
A: People often ask about the Oxalis triangularis toxic properties. Pets don’t have the same restraint that we do. The oxalic acids are much more potent against smaller pets. It can cause drooling, vomiting, diarrhea, and a lack of appetite, among other symptoms. Thankfully, its bitter flavor tends to prevent most pets from chewing on it! But if your dog isn’t deterred and sees it as an edible plant, keep it away.
Q: Is Oxalis triangularis invasive?
A: Unlike many other oxalis species, it does not tend towards invasive. It does spread, but not as fast as other types of oxalis.
Q: How do you care for Oxalis triangularis?
A: Caring for an Oxalis triangularis plant is pretty easy! Take a look at our guide for more details about how to help it establish itself in your garden.
Q: Does Oxalis triangularis need direct sunlight?
A: In cooler climates, the purple shamrock of Oxalis triangularis needs full sun. In hotter climates, give it some shade. In both cases, these plants need bright light in some form.
Q: Is Oxalis triangularis indoor plant?
A: It certainly can be! Oxalis triangularis is adaptable to both indoor and outdoor conditions.
Q: Where should Oxalis triangularis be placed?
A: It depends on how you grow Oxalis triangularis. If you grow indoors, give it a spot with plenty of sunlight. If you are growing outdoors, consider the ambient temperature before planting or placing your container. High heat warrants some shade, whereas cooler conditions mean Oxalis triangularis needs more direct sunlight.
Q: Why is my Oxalis plant dying?
A: There are a couple of different reasons why Oxalis triangularis might be dying. Check the Troubleshooting section above to see if it could be one of those issues.